ARM, previously Advanced RISC Machine, originally Acorn RISC Machine, is a family of RISC architectures for computer processors, configured for various environments. Arm Holdings develops the architecture and licenses it to other companies, who design their own products that implement one of those architectures—including systems-on-chips (SoC) and systems-on-modules (SoM) that incorporate memory, interfaces, radios, etc. It also designs cores that implement this instruction set and licenses these designs to a number of companies that incorporate those core designs into their own products.


Processors that have a RISC architecture typically require fewer transistors than those with a complex instruction set computing (CISC) architecture (such as the x86 processors found in most personal computers), which improves cost, power consumption, and heat dissipation. These characteristics are desirable for light, portable, battery-powered devices—including smartphones, laptops and tablet computers, and other embedded systems[1][2][3]—but are also useful for servers and desktops to some degree. For supercomputers, which consume large amounts of electricity, ARM is also a power-efficient solution.[4]

With over 130 billion ARM processors produced,[5][6][7][8] As of 2019, ARM is the most widely used instruction set architecture (ISA) and the ISA produced in the largest quantity.[9][2][10][11][12] Currently, the widely used Cortex cores, older "classic" cores, and specialized SecurCore variants are available for each of these to include or exclude optional capabilities.

Apple and ARM

In the late 1980s, Apple Computer and VLSI Technology started working with Acorn on newer versions of the ARM core. In 1990, Acorn spun off the design team into a new company named Advanced RISC Machines Ltd.,[13][14][15] which became ARM Ltd when its parent company, Arm Holdings plc, was floated on the London Stock Exchange and NASDAQ in 1998.[16] Apple invested US$3 million for a 30% stake in the venture.[15] The new Apple-ARM work would eventually evolve into the ARM6, first released in early 1992. Apple used the ARM6-based ARM610 as the basis for their Newton PDA. However, with disappointing sales, Apple closed down the Newton Systems Group in 1998 and sold its stake in ARM for $800 million in desperately needed cash.[17]

In 2001, Apple released the first iPod, which used a ARM-based processor from PortalPlayer and ran an operating system designed by Pixo, which was co-founded and staffed by former Newton employees.[17][18]

Apple licensed ARM technology for the A4, A5, and A5X and other early processors used in its iPhone and iPad lines. However, Apple acquired P.A. Semi for $278 million in April 2008 to bring fabless processor design in-house to the company.[19] The Apple A6 contained a custom CPU designed internally at Apple (called "Swift") instead of one licensed from ARM.[20]


  1. "Some facts about the Acorn RISC Machine" Roger Wilson posting to comp.arch, 2 November 1988. Retrieved 25 May 2007.
  2. 2.0 2.1 Hachman, Mark. "ARM Cores Climb Into 3G Territory", ExtremeTech, 14 October 2002. Retrieved on 24 May 2018. (in en-US) 
  3. Turley, Jim. "The Two Percent Solution", Embedded, 18 December 2002. Retrieved on 24 May 2018. (in en) 
  4. Fujitsu drops SPARC, turns to ARM for Post-K supercomputer (20 June 2016). Retrieved on 18 December 2016.
  5. Architecting a smart world and powering Artificial Intelligence: Arm (en) (2019). Retrieved on 2020-04-08.
  6. Ltd, Arm. Microprocessor Cores and Technology – Arm (en). Retrieved on 2020-04-08.
  7. Enabling Mass IoT connectivity as Arm partners ship 100 billion chips (en). Retrieved on 2020-04-08. “the cumulative deployment of 100 billion chips, half of which shipped in the last four years. [..] why not a trillion or more? That is our target, seeing a trillion connected devices deployed over the next two decades.”
  8. Ltd, Arm. Microprocessor Cores and Technology – Arm (en). Retrieved on 2020-04-08.
  9. MCU Market on Migration Path to 32-bit and ARM-based Devices: 32-bit tops in sales; 16-bit leads in unit shipments. IC Insights (25 April 2013). Retrieved on 1 July 2014.
  10. Turley, Jim (2002). The Two Percent Solution.
  11. ARM Holdings eager for PC and server expansion (1 February 2011).
  12. Kerry McGuire Balanza (11 May 2010). ARM from zero to billions in 25 short years. Arm Holdings. Retrieved on 8 November 2012.
  13. ARM milestones, ARM company website. Retrieved 8 April 2015
  14. Jason Andrews. "Co-verification of hardware and software for ARM SoC design", Elsevier, pp. 69. “ARM started as a branch of Acorn Computer in Cambridge, England, with the formation of a joint venture between Acorn, Apple and VLSI Technology. A team of twelve employees produced the design of the first ARM microprocessor between 1983 and 1985.” 
  15. 15.0 15.1 Weber, Jonathan. "Apple to Join Acorn, VLSI in Chip-Making Venture", Los Angeles Times, 28 November 1990. Retrieved on 6 February 2012. “Apple has invested about $3 million (roughly 1.5 million pounds) for a 30% interest in the company, dubbed Advanced Risc Machines Ltd. (ARM) [...]” 
  16. ARM Corporate Backgrounder. ARM Limited. Archived from the original on 4 October 2006.
  17. 17.0 17.1 How The Newton And ARM Saved Apple From Death, The CPU Shack Museum. 2010-10-26.
  18. Little-known startup was behind iPod's easy-to-use interface / Firm's founder now working on the latest handhelds by Matthew Yi, San Francisco Chronicle. 2004-08-16.
  19. "Apple Buys Chip Designer", Forbes. Retrieved on 2008-04-23. 
  20. The iPhone 5 Review - Decoding Swift. AnandTech (October 16, 2012). Retrieved on October 17, 2012.

See also

External links

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